The evolution of integrated circuits has resulted in electronic devices that have decreased in size and increased in speed, power dissipation and density. As power dissipation of electronic devices has increased, so has the need for better thermal management techniques. For example, current thermal management techniques for flip chip packaged electronic devices are generally only capable of providing a power density of 40 W/cm2. However, future flip chip packaged devices may require power densities of 125 W/cm2, or greater. As mentioned above, current thermal management techniques are unsatisfactory for these levels of required thermal conductivities. Thus, without better thermal management solutions, chip size may have to be increased or the performance (i.e., speed) of the chip may need to be decreased, which, in general, provides a less desirable end-product.
Traditionally, thermal management has been achieved by utilizing aluminium heat sink pedestals that are in thermal contact with a non-active side of a flip chip (or other electronic device package) and have utilized dispensed thermally conductive grease or adhesive positioned between the non-active side of the flip chip and the heat sink pedestal to increase the thermal conductivity between the flip chip and the pedestal. Unfortunately, using thermal grease to increase heat transfer between the flip chip and the heat sink pedestal can be a messy proposition. Further, thermal grease typically only provides a modest increase in heat transfer as the thermal conductivity of the grease is relatively poor, generally in the range of 0.7 W/m K, as compared to a heat sink pedestal backplate, which may have a thermal conductivity over 200 W/m K.
In assemblies implementing such a configuration, a silicon elastomer has usually been positioned within the assembly to force the flip chip in contact with the pedestal backplate. Other assemblies have utilized different thermally conductive materials between the heat sink pedestal and a non-active surface of the flip chip, such as thermal films or pads. However, these thermal materials are usually applied through hand placement or using automated pick-and-place techniques. In general, such thermal films or pads improve thermal conductivity between the flip chip and the pedestal. For example, some thermally conductive film or pads may have a thermal conductivity of up to 7.5 W/m K. However, in general, the utilization of greases and thermally conductive films and pads provide a heat transfer on the order of one to two magnitudes below the thermal conductivity of the pedestal backplate.
What is needed is a thermal management technique that provides for increased thermal conductivity between an integrated circuit (IC) chip and an associated heat sink pedestal backplate.